Fugu Ultra v2 is $5 cheaper per 1M input tokens (50% lower; 2x difference).
API cost decision in 10 seconds
NewFugu Ultra v2 vs NewGPT-6 Astra Pro
Pick Fugu Ultra v2 for lower cost; pick GPT-6 Astra Pro only if the larger context window matters more.
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Data confirmed:
Prices normalized to USD per 1M tokens
Sample workload: 1M input + 500K output
Budget verdict
Pick Fugu Ultra v2 for lower cost; pick GPT-6 Astra Pro only if the larger context window matters more.
On the standard 1M input plus 500K output workload, Fugu Ultra v2 is estimated at $20 vs $35 for GPT-6 Astra Pro, saving $15 (42.9% lower).
Cost-first pickFugu Ultra v2
Context-first pickGPT-6 Astra Pro
Sample savings$1542.9%
10x traffic gap$150
GPT-6 Astra Pro has more context, but Fugu Ultra v2 saves $15 on the standard workload. At 10x that traffic, the same price gap is about $150. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
Fugu Ultra v2 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | Fugu Ultra v2 | GPT-6 Astra Pro |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | Fugu Ultra v2 | $40 | $75 |
| Balanced workload | 1M input + 1M output | Fugu Ultra v2 | $35 | $60 |
| Output-heavy chatbot | 1M input + 5M output | Fugu Ultra v2 | $155 | $260 |
Fugu Ultra v2 is $20 cheaper per 1M output tokens (40% lower; 1.67x difference).
GPT-6 Astra Pro has 50K more context (1.05x larger).
Fugu Ultra v2 is $15 cheaper on the standard workload (42.9% lower).
Estimate your workload cost
Your Workload Cost
This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.
Quick Decision
Fugu Ultra v2 has the lower input price; Fugu Ultra v2 has the lower output price; GPT-6 Astra Pro offers the larger context window. For the 1M input plus 500K output sample, Fugu Ultra v2 is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $20 for Fugu Ultra v2 and $35 for GPT-6 Astra Pro.
Choose Fugu Ultra v2 when you care most about lower input-token price, and lower output-token price.
Choose GPT-6 Astra Pro when you care most about larger context window.
- On the standard 1M input plus 500K output workload, Fugu Ultra v2 is estimated at $20 vs $35 for GPT-6 Astra Pro, saving $15 (42.9% lower).
- Fugu Ultra v2 is $15 cheaper on the standard workload (42.9% lower).
- Fugu Ultra v2 is $5 cheaper per 1M input tokens (50% lower; 2x difference).
- Fugu Ultra v2 is $20 cheaper per 1M output tokens (40% lower; 1.67x difference).
- GPT-6 Astra Pro has 50K more context (1.05x larger).
| Feature | NewFugu Ultra v2 (Sakana) | NewGPT-6 Astra Pro (OpenAI) |
|---|---|---|
| Input Price prompt tokens per 1M | $5 | $10 |
| Completion Price per 1M tokens | $30 | $50 |
| Sample Workload Cost 1M input + 500K output | $20 | $35 |
| Context Window | 1M | 1.05M |
| Release Date |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | Fugu Ultra v2 | On the standard 1M input plus 500K output workload, Fugu Ultra v2 is estimated at $20 vs $35 for GPT-6 Astra Pro, saving $15 (42.9% lower). |
| High-volume input processing | Fugu Ultra v2 | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | Fugu Ultra v2 | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | GPT-6 Astra Pro | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- Sakana Namazu can replace Fugu Ultra v2 when lower sample workload cost matters most: $2.95.
- Fugu Max can replace Fugu Ultra v2 when lower sample workload cost matters most: $5.
- gpt-oss-120b (free) can replace GPT-6 Astra Pro when lower sample workload cost matters most: $0.
- gpt-oss-20b (free) can replace GPT-6 Astra Pro when lower sample workload cost matters most: $0.
- Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
- Grok 4.20 offers 2M context with $2.5 sample workload cost.
- GLM 5.3 Flash offers 1.31M context with $0.4 sample workload cost.
- DeepSeek V4 Flash 0731 offers 1.31M context with $0.08 sample workload cost.
- Hy4 preview · Tencent · #1
- GPT-5.6 Luna · OpenAI · #2
- GLM 5.3 Flash · Z.ai · #3
- DeepSeek V4 Flash 0731 · DeepSeek · #4
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Open OpenAI modelsFugu Ultra v2 is the higher-performance model in Sakana AI's Fugu family. Rather than a single monolithic model, Fugu is a learned multi-agent orchestration system: a language model trained to...
GPT-6 Astra Pro is the same underlying model as [GPT-6 Astra](https://openrouter.ai/openai/gpt-6-astra), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode